Signal geo-coding is the process of assigning geographic coordinates to a signal. The signal coordinates can include the geographic coordinate of the transmitter as well as that of the receiver. In many locations there may be an abundance of events within a small area called a bin. A bin may include a multi-story building with a number of subscribers at each floor or it may include some other structure. While some bins can generate a number of events, others may show a lack of activity. If there are many events in a bin, a histogram of signal levels and corresponding path loss data can be constructed. If sufficient data is unavailable for a sector, interpolation techniques can be used from other bins to construct a working model. The model can provide some guidelines in frequency reuse planning and interference avoidance.
Typically there are too few measurements of interference from a sector in the vicinity of the bin to determine an accurate service level. If a sufficient amount of data has been collected, ignoring sector interference may be justified. However, in most cases the system administrator relies on information that only provide average signal level (or path loss) at a bin. The system administrator does not know whether the average values were determined based on a few or many measurements. Moreover, the average values often misrepresent signal propagation characteristics of a bin.
In bins that have an abundance of data, there may be a range of signal levels and interference levels. In these situations relying on average signal level values will prove ineffective as these values do not reflect the true propagation characteristics of the bin. In many instances the signal levels are known to change dramatically within a distance of, for example, ten meters. This is especially true in-building measurements are considered.
Conventional planning tools produce an average estimate of the signal level or path loss value per bin for each sector under consideration. Such measurements ignore a tremendous amount of valuable information about the propagation characteristics within a bin. For example, when power levels or antennas are being optimized to minimize overall network interference it is valuable to maintain paired signal levels or path losses that consider the location of the transmitter and the receiver as well as the signal attributes transmitted therebetween.
Consider a situation where a bin contains a tall building and the serving cell antenna is located some distance away on top of another tall building. At street level and in the lower levels of the building the serving signal level and the interfering signal level may both be low. On the upper levels of the building the interfering signal levels may increase as would the serving signal level. Relying on an average signal level for the entire building will dilute this valuable information. Using the average serving and interfering signal levels grossly undermines the true propagation characteristics of the bin and leads to a substantial over-estimate of the severity of the interference.
On the other hand, in a situation where a serving cell antenna is located nearby on the tall building on a two- or three-story building, the serving cell may be substantially stronger and interference substantially weaker for the lower levels of the building. For the higher levels of the tall building, the serving level may be lower but the interference level may be higher. In this case, the serving and the interfering signal levels would be negatively correlated. Again, an average serving signal level, interference or path loss calculation will not provide sufficient detail of the propagation characteristics. Therefore, there is a need for obtaining propagation information which accurately couples signal levels at different locations within a bin with the serving base stations that provide the signal at said locations.